Indicating gas-mask canister



May 12, 1925.

M. YABLlCK INDIGATING GAS MASK CANISTER Filed Dec. 5, 1924 NIH INVENTQRMarJ'Zzfi/zb/r BY I My ATTORNEYS Patented May 12, 1925.

UNITED STATES PATENT OFFICE.

MAX YABLICK, OF NEW YORK, N. Y.

INDICATING GAS-MASK CANISTER.

Application filed lpecember 5 1924. Serial No. (54,108.

To all whom it may concern: 7

Be it known that I, MAX YABLIGK, a citizen of the United States, andresident' of New York, in the county of New York and State of New York,have invented certain new and useful Improvements in Indicating Gas-MaskCanisters, of which the following is a specification.

My present invention relates primarily to respirators and moreparticularly to the canisters thereof for intercepting or separating outpoisonous or obnoxious gases from air, drawn therethrough in the processof inhalation.

Since an ordinary canister comprising a metal cas ng enclosing the gasabsorbing or intercepting composition through which the air is drawn,does not indicate the extent of residual life after use, such canisterwhen reused, may fail at such time as it is most needed, whilediscarding of a canister after but a single use usually involves waste.

It is accordingly, among the objects of the invention to provide acanister which will indicate while in or out of use, without the needfor separate testing appliances or operations, the proportion ofresidual life therein.

Another object is to provide indicating means for the purpose mentionedwhich shall not necessitate any substantial change in the constructionor design of canisters in commonuse, which shall in no way interferewith the efficacy of the-canister in the regular performance of itsfunction, nor involve added d scomfort or danger in use,

which shall operate reliably without possibility of a falseregistration, which shall involve no delicate mechanical or otherappliances likely to;become out of order, and.

which shall not add' appreciably to the cost of the canister.

My present invention has a preferred field of application to canisters,the fillers of which preferably of granular material, have a'markedavidity for the impurity to be intercepted, absorbed, adsorbed oroccluded.

the first illustration.

after it has intercepted the gaseous impurity, the indication can beeffected through a window in the canister extending the height thereofor by providing a transparent can'- ister wall. On the other hand, wherethe gas does not change the color or'appearance of the filler, thelatter may be impregnated with an appropriate indicator for the gas, sothat the indication can be effected as in Where it is not desiredto usean indicating impregnation, an indicator test strip may be used,extending the height of the canister in contact with the filler, andpreferably superposed over the inner wall of the canister,- and exposedthrough a transparent or open wall portion, or the container wall itselfor a partthere-v of may be of an absorbent material impregnated with theindicator, and exteriorly covered with a transparent gas resistingcoatin", such as shellac.

In the present application, I claim generically the various alternativeembodiments and applications herein disclosed and specifically theapplication to a respirator for abstract ng ammonia and utilizing afiller which inherently changes color when combined with the ammonia.All novel'subjectmatter including the application of a separateindicator and also the detailed me- 'chanical construction ofthecanister and more especially of the window are claimed in mvcopendino' d visional application, Serial No. 18,161 filed March 25th1925.

In the accompanying drawings in which is shown one or more of variouspossible embodiments of the several features of this invention;

Fig. 1 is a side view of a preferred canister,

Fig. 2 is a view in longitudinal section taken along the line 22 of Fig.1, and;

Fig. 3 is a fragmentary longitudinal sectional view of a modification.

The casing of the canister is substantially conventional, including theusual shape The filler 15, preferably a granular substance, may besupported upon a layer 116 of absorbent cotton, in turn, upon a curved.wire mesh seat 17 above the flap valve 11,. affording a space 18 inwhich" the flap valve comprismg a narrow strip of transparent deringasat 2'5.

material such as glass held in place in the canlster 1n any of a widevarlety of manners.

By way'of lllliSllIfitlQIl, I have shown the windon lodged in anintegral rectangular.

frame .24, pressed outward from the metal of the canister and fixed inposition by sol- Ifreferably the window is a thick pane of triplex oriion-shatterable glass comprising twothinner panes of glass cemented toan interposed sheet 23 of celluloid or the like. The inner wall of pane25 may be provided'with a series of prisms 26 extending horizontallythereacross in contact with the absorbent filler for a purpose whichwill appear fully in the operation set forth below.

The filler it will be understood is of composition and physical.construction such as to have a particular affinity or avidity for thegas or gases to be abstracted from. the air drawnthrough'the canisterinto the lungs of the user. In certain applications, the canistercontents will change color or appearance when the gas has been absorbed.

thereby, for instance, in the use of a filler of copper sulphatecrystals, impregnating granules of pumice stone or the like, the naturalgreen color changes to blue when ammonia has replaced the water ofcrystallization in whole or in part.

As the ammonia laden air is drawn-into the canister, the ammonia/willrapidly be absorbed by the bottom layer of the filler and air freed fromammonia is drawn pregnate the absorbent with an indicator,- a

through the rest of the filler; so that the ammonia saturated compoundat the bottom of the-canister, will appear blue after use, while therest of the filler above said bottom will remain green. By inspectionthrough the window, therefore, .it is instantly ascertained whatproportion of the lifeof the canister--has been spent and to what extenttherefore, the canister is available for further use.

The presence of the multiplicity of transverse ribs on the windowagainstwhich the granular contents in the canister is firmly pressed,obstructs any possible relatively free path for the air along theminutegap, whlch might otherwise exist between the window and the contents,and thereby avoids the possibility of the impurity in the air when drawnthrough the canister, rapidly-changing the c0101 of the entire length offiller exposed through the window, and giving a false indication wherethe body' of the filler is not spent. By the rib construction, it isseen that the air is not readily drawn throughthe path of greatlyincreased resist- -In some cases, however, the filler will not change incolor or physical appearance after it has absorbed the impurity on whichit is toact, sufiiciently to afford a line. of demarcation between thesaturated and the freshpart. In such case, it is desirable to combinewith the filler an appropriate indi- 'cator which will change color bythe action of the impurity, the indicator, of course, in

each case being such as not to impair the efiicacy of normal operation.For instance, the usual filler of soda lime employed as an absorbent forhydrogen sulphide does not appreciably change color after it has beensaturated by the gas, so that the residual life ofthe canister could notreadily be ascertained by inspection through the window. In this case, Ipreferably spray the soda lime with a solution of lead salt. such aslead acetate. The lead salt, as will be understood, is converted intothe black lead sulphide, when acted on by the hydrogen sulphide, so thatit serves as an indicator, the filler now appearing black to the levelto which the free hydrogen sulphide gashas passed. Instead of spraying,the absorbent can, ofcourse, be immersedin a solution of the. salt.

. r v v Where itis undesired or unfeasible to 1mseparate test orindicator stri 27 may be used, applied immediately bac of the window23*, as shown in Fig. 3. This test strip vmay either be of a type whichchanges color when acted on by the gaseous impurity itself or when actedon by the product resulting from the absorption of the gaseous impurityby, or other actionupon thefiller. In the case of a canister forremoving ammonia gas, embodying a filler of material that does notinherently change color after it has been used, such, for instance, assilica v gel, ordinary red litmus paper may beused,

. color to the level to which its contents has been spent.

During the actual use, in industry, of a canister, as for the protectionfrom ammonia, chlorin, sulphur dioxide, hydroc mic or hydrochloric acid,a faint odor of t ese gases will apprise the user to change canisters,even if he should not look at the indicator, which in that case wouldappear to show that'the canister has been spent. In the case of acanister used for protection against carbon monoxide, however, or otherpoisonous gas that is odorless and tasteless, the canister should belooked at by the user from time to time during service, only theindicator in that case and neither the'sense of smell, taste, or anyother sense or sensation, apprising of the need for changing canisters.Without my indicating means in the use of a canister operating ina-carbon monoxide atmosphere, the user might be seriously poisonedbefore he became aware of the fact that the canister is not func-.

tioning. Inasmuch asin the use of a carbon monoxide abstractingcanister, the availability for further use should be almost constantlyascertained during actual service,

it might be-desirable to extend the indicator, not throughout the heightof the canister, but only near the top thereof, the change in color orappearance duripg service, of such indicator, apprising ofthe need forchanging canisters. A small mirror (not shown) is, therefore,advantageous, set at the proper angle to reflect the image of theindicator, so that it can be constantly seen, while the mask is in use.

My indicator -always apprises'of the need for replacing the canister,even though the latter may not be entirely spent, but by reason of rapidbreathing, for instance, the impurity might only have acted on thesurface of the granules throughout the hei ht of the canister andthereby have cause a change in color throughout the height of thewindow. I

When the canister thus used, is laid aside for-a period of hours ordays, the granules which have only absorbed the gas at their surface,resume substantially the color or appearance of the unspent granules, byrea-' son of the im urity spreading throughout the volume 0 thegranules, while those granules that have been saturated maintain thecolor or appearance of spent filler. Ac-

demarcation between the spent and unspent part thereof, visible throughthe Window. The user, accordingly, knows that it is still serviceable,where, in the absence of my indicating means, or separate testingappliances or operations, he would not feel safe in re-using a canisterthat had once apparently failed.

I have thus provided a reliable registering means for indicating theresidual life of the canister and its availability at any instant forfurther use, which means is simple and easy to apply, which involves nodelicate mechanism of any character, which avoids the use of specialtesting appliances or the need for disassembly of the apparatus, whichdoes not depend for its operation T on temporarily inflicting discomfortor pain upon the user and which does not inipair the life of thecanister. Should the canister drop and the glass window crack,

the celluloid pane therein remains intact and prevents the entry of airor gas through the crack, so that false reading is avoided.

Where a special chemical is used, near the top of the canister toproduce a special noticeable physiological efl'ect, such as to excitethe lachrymal glands, as a signal that the canister is no longer fit foruse, it is apparent that there is no means available for indicating tothe user, the extent to which the canister is still available, when, heis about to commence its use, so that after use but for a fraction of aminute, the signal may be given and the user is compelled to leave thegas-charged space and obtain a new canister. Moreover, the efliciency ofthe worker-is impaired, by the anticipation of the pain and discomfortto be inflicted and by the actual damage done when the alarm is given.

Where, on the other ,hand, two or more canisters are carried on theperson with an inter-connecting valve for placing a used.

canister out of service and changing to a supposedly unused canister,not only is the apparatus more bulky and of greater weight, impairingthe freedom of movement of the user, but, unless the connecting valve isparticularly well made at substantial expense, it is likely to leak, sothat as a matter of fact, the two canisters will to an extent be usedconcurrently and the supposedly fresh reserve canister may actually bespent or nearly spent, when the valve is set to bring it into use.

4 In the foregoing, .I have described two specific applications orembodiments of the invention suitable for ammonia and one for hydrogensulphide gas masks. For abstracting sulphur dioxide, soda lime may beused as with hydrogen sulphide, with a separate indicating test paper,however, impregnated with potassium iodate starch .and appliedsubstantially as in the embodiment of Fig. 3. For abstractinghydrochloric acid fumes, soda lime is also suitable, but as in its usefor removing-sulphur dioxide or hydrogen sulphide, it does not changecolor. For this use, it is preferable to impregnate the soda lime with aCongo red solution which turns blue when acted on by hydrochloric acidfumes. For removing carbon monoxide gas, a suitable absorbent may beused, with palladium chloride test paper, serving as an indicator andturning dark under the action of carbon monoxide. Another suitableindicator for carbon monoxide is iodine pentoxide, sulphuric acid. Theforegoing are illustrative examples merely of noxious gases and theindicators therefor with which my invention is concerned.

My invention is not limited in its application to industrial uses, butis suitable also in chemical warfare. In military'operations, thus, whenthe window or other in dicating area shows no more change, the soldierknows it is safe to remove the mask, and thus the dangers of prematureremoval, as well as the discomfort of continued use of the mask when nolonger necessary, are obviated.

It will thus be seen that there is herein described apparatus in whichthe several features of this invention are embodied, and which apparatusin its action attains the various objects of the invention and is wellsuited to meet the requirements of practical use.

As many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

I claim v 1. A respirator canister having. an air inlet at one endthereof and an outlet at the other, a filler for said canister forabstracting a definite impurity 'from air drawn therethrough, saidfilter including a part extending substantially the distance between theends of the canister and subject by contact with said impurity to changein appearsubstantially the entire length between said inlet and saidoutlet, means filling said canister and having an aflinity for animpurity to abstract the latter from air inhaled through the canister,and subject by contact with said impurity to change in appearance,whereby said window will visually indicate the region of demarcationbetween the spent and the unspent filler.

3. A respirator canister having an inlet at the lower and an outlet atthe upper end thereof, a transparent portion extending substantially theheight of said canister, a filler in said canister having a strongalfinity for a definite gas to abstract the latter as air chargedtherewith is drawn therethrough, said filler composition being of typeto change color when acted upon by said gas, whereby theline ofdemarcation between the spent or used composition at the bottom and theavailable composition thereabove may be readily ascertained byinspection.

4. A respirator canister having a transparent portion extending theheight thereof, a solid composition filling the same and having a strongaflinity for a definite gaseous impurity drawn through the filler withair, the composition combined with the-gas inter- .cepted thereby havinga different appearance to the eye than prior to such combination,whereby a line of demarcation will appear between the spent part of thefiller at the bottom of the canister and the unspent part thereabove.

5. A respirator for abstracting ammonia, comprising a canister having atransparent part extending substantially from one end to the otherthereof, a filler of a metallic salt to form addition products withammonia passed therethrough of color other than theuncombined salt,whereby the line of demarcation between the combined and the uncombinedsalt will indicate the residual life of the canister.

Signed at New York in the county of New I York and State of New Yorkthis 26th day of November A. D. 1924.

MAX YABLICK.

